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Photography Exposure

What is Rolling Shutter – What Causes It?

July 2, 2023 by

Imagine you’re standing on the sidewalk of a bustling street, ready to capture a perfectly frozen moment of cars going by.

As you press the shutter button and take a photo, you can’t wait to check out the image to see how it looks.

As you look at the image, you’ll find something peculiar — a distortion that stretches and skews the image.

Well, what you’ve encountered is the “rolling shutter” effect, a common annoyance for both photographers and videographers.

To understand this phenomenon, let’s take a closer look at what a rolling shutter is, how it works, and more.

Let’s dive in!

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What is Rolling Shutter?

Rolling shutter is a peculiar phenomenon that occurs when capturing images or videos using cameras equipped with a specific type of sensor.

Unlike traditional global shutters that capture an entire frame simultaneously, cameras with rolling shutters capture the scene by scanning it progressively, either from top to bottom or left to right.

cmos sensor rolling shutter
CMOS sensor scanning up and down

This sequential scanning introduces a time difference between the capture of different parts of the image, resulting in potential distortions.

Shutter speed — a critical component of the exposure triangle along with aperture and ISO, is a fundamental aspect of photography that determines the duration for which the camera’s shutter remains open, allowing light to reach the image sensor or film.

It directly affects the exposure of the image and has a significant relationship with the rolling shutter effect.

Where global shutters are used, the shutter speed controls the duration for which the entire frame is exposed to light simultaneously. The shutter opens, allows light to enter the camera, and then closes, capturing a complete, instantaneous image.

However, in cameras with rolling shutters, the scanning process introduces a time delay between the capture of different parts of the image.

As a result, the effective exposure time for each line or row of the image may vary slightly depending on when it was scanned. This discrepancy in exposure time can lead to distortions and artifacts when capturing fast-moving objects or scenes.

The relationship between shutter speed and the rolling shutter effect becomes evident when there is significant movement within the scene.

A faster shutter speed, which means a shorter exposure time, can help minimize the impact of rolling shutter artifacts. With a shorter exposure, there is less time for movement to occur during the scanning process, resulting in a reduced likelihood of distortion.

On the other hand, a slower shutter speed, with a longer exposure time, can exacerbate the rolling shutter effect. When the shutter remains open for an extended period, there is more opportunity for movement to take place during the sequential scanning, leading to pronounced distortions and skewing of the image.

Here are a couple of examples where I’ve noticed you can easily find the demonstration of a rolling shutter effect:

1. Wobbly Buildings

The first example is with wobbly buildings.

For example, if you take an image that is near objects such as tall buildings and there is motion blur, you may notice that the buildings appear slightly bent or distorted.

This distortion is a classic rolling shutter artifact. As the camera scans the image from top to bottom, any movement of the buildings during the scan results in an irregular shape.

The taller the buildings, the more pronounced the distortion becomes, leading to a surreal and wobbly effect.

For example, in this image, the building should be vertical, however, it looks like it’s leaning:

wobbly building rolling shutter
wobbly building rolling shutter

2. Spinning Blades or Wheels

The second example is with spinning blades or wheels.

Let’s say you’re photographing a fan or spinning blades on a helicopter or airplane. If you take a photograph of them they will appear warped or fragmented.

As the camera scans the image, each blade or fan’s position is captured at a slightly different time, resulting in an uneven representation of the rotating blades.

The faster the blades spin, the more pronounced the distortion becomes, often giving an otherworldly appearance to your final image or video.

Here’s an example of this by the channel SmarterEveryDay. Be sure to check out the video, it gives a great explanation:

rolling shutter spinning blades
Image from video by SmarterEveryDay

What is the Cause of Rolling Shutter?

Rolling shutter is primarily associated with cameras that utilize CMOS (Complementary Metal-Oxide-Semiconductor) image sensors. CMOS sensors are widely used in digital cameras and smartphones due to their cost-effectiveness, low power consumption, and versatility.

However, their scanning mechanism is what contributes to the rolling shutter effect.

When capturing an image or video, a CMOS sensor scans the scene line by line, either from top to bottom or from left to right.

This scanning process introduces a time delay between the capture of different parts of the image.

Any movement that occurs during this scanning period can result in the characteristic rolling shutter distortion.

In contrast, cameras equipped with CCD (Charge-Coupled Device) sensors typically employ global shutters, capturing the entire frame simultaneously.

This simultaneous capture ensures that all parts of the image are recorded at the same moment, minimizing or eliminating the rolling shutter effect.

It’s worth noting that while rolling shutter is most commonly associated with CMOS sensors, not all CMOS-based cameras exhibit the same degree of rolling shutter artifacts.

Different camera models and manufacturers employ various strategies to mitigate the effect, such as implementing faster readout speeds or utilizing electronic or mechanical shutter mechanisms in conjunction with the CMOS sensor.

It’s important to check whether your camera states whether it has rolling shutter or not.

This sequential scanning introduces a time difference between the capture of different parts of the image, resulting in potential distortions.

How to Fix the Rolling Shutter Effect?

In order to fix the rolling shutter effect, the best solution is to just avoid using a camera with a CMOS sensor that has rolling shutter.

Fixing the rolling shutter effect can be challenging, as it is primarily a characteristic of the camera’s hardware and sensor design.

It’s important to remember that not all CMOS sensor cameras are associated with rolling shutter and there have been many advancements in sensor technology and camera design that have allowed manufacturers to mitigate rolling shutter distortions.

For example, with the Canon EOS 5D Mark IV, it uses a CMOS sensor and has been shown to have significant rolling shutter.

If you don’t want to chance it, the best solution is to make sure you research your camera before buying it.

But it’s also important to remember that capturing the rolling shutter effect happens only in very specific instances.

Ask yourself if you find yourself in any of these scenarios often. If you say yes to any of them then make sure to find a camera without rolling shutter but if you say no then you most likely won’t encounter it:

  1. When attaching a camera to a moving vehicle: Cameras without significant rolling shutter artifacts are preferable when mounting them on moving vehicles to capture smooth and distortion-free footage. This ensures that the motion of the vehicle does not introduce unwanted distortions or skewing in the resulting images or videos.
  2. When attaching a camera to vibrating objects: Cameras with reduced rolling shutter effects are beneficial when attaching them to objects that experience vibrations, such as helicopters or drones. By minimizing rolling shutter artifacts, these cameras help maintain the integrity of the captured footage despite the vibrations, resulting in clearer and more stable imagery.
  3. When capturing fast action sports: Cameras with minimal rolling shutter are ideal for capturing fast-action sports, where quick and precise movements occur. Such cameras can help minimize the distortion of rapidly moving subjects, allowing for more accurate and detailed representation of the action.
  4. When frequently panning or tracking rapidly: Cameras with minimal rolling shutter artifacts are advantageous for photographers or videographers who frequently engage in rapid panning or tracking movements. By reducing rolling shutter effects, these cameras ensure that the motion appears smooth and coherent, preserving the integrity of the captured visuals.
  5. When capturing subjects moving quickly past the camera: Cameras with minimal rolling shutter are beneficial for scenarios where objects move swiftly past the camera. By minimizing the distortions caused by the rolling shutter effect, these cameras can accurately capture the motion and preserve the visual integrity of the passing subjects.
  6. When shooting slow-motion footage with vertical edges: Cameras with reduced rolling shutter effects are particularly useful when shooting slow-motion footage that involves vertical edges, such as buildings, while simultaneously moving the camera. Minimizing rolling shutter artifacts helps maintain the vertical integrity of the structures, preventing them from appearing skewed or distorted during slow-motion playback.

How to Prevent the Rolling Shutter?

Now that you know how to fix rolling shutter — how would you prevent it?

1. Use a Camera With Global Shutter

The first way to prevent rolling shutter is to use a camera with global shutter.

Global shutters capture the entire frame simultaneously, eliminating the sequential scanning process responsible for rolling shutter distortions.

Cameras equipped with global shutters are less susceptible to rolling shutter artifacts.

However, it’s important to note that cameras with global shutters are less common in consumer-grade models and are typically found in higher-end professional cameras.

2. Use Cameras with Fast Sensor Readout Speeds

The second way to prevent rolling shutter is to opt for cameras with fast sensor readout speeds.

Cameras with faster sensor readout speeds reduce the time difference between the scanning of different parts of the image, thereby minimizing the rolling shutter effect.

Look for cameras that advertise fast readout speeds, as they tend to exhibit fewer rolling shutter artifacts.

3. Choose a Faster Shutter Speed

The third way to prevent rolling shutter is to choose a faster shutter speed.

Selecting a faster shutter speed reduces the exposure time, limiting the opportunity for motion to occur during the scanning process.

By opting for a quicker shutter speed, you can minimize the likelihood of capturing rolling shutter distortions.

Experiment with different shutter speeds to find the optimal setting for your specific shooting conditions.

How to Get the Rolling Shutter Effect?

So after learning about the rolling shutter effect, let’s say you want to purposely get this effect — how would you go about doing that?

Here are a few ways to intentionally capture this effect that I’ve found work best (you’ll need to have a camera that has a CMOS sensor and rolling shutter, you can try this on your smartphone as most cameras have a CMOS sensor):

1. Intentionally Move Your Camera

One way to simulate the rolling shutter effect is by intentionally moving your camera during exposure.

By deliberately shaking or panning the camera while taking a photo or recording a video, you can mimic the sequential scanning of a rolling shutter.

This technique works particularly well when capturing moving subjects or scenes with prominent lines and shapes. Experiment with different levels of camera movement to achieve the desired amount of distortion and artistic impact.

For example, when photographing a moving car, try panning the camera in sync with the car’s motion.

The resulting image will showcase elongated or skewed features, emulating the characteristic rolling shutter effect. This technique can evoke a sense of speed and dynamism in your visuals.

camera panning
camera panning

2. Whip Panning With Your Camera

The second way to simulate the rolling shutter effect is with whip panning.

Whip panning involves swiftly moving your camera from one side to another while taking a photo or recording a video.

This technique creates a dramatic motion blur effect and introduces a rolling shutter-like distortion. It works best when capturing subjects with distinct linear elements, such as cityscapes, architectural structures, or crowds in motion.

For example, let’s say you’re standing on a busy street corner during rush hour. As you whip pan the camera, the buildings and people within the frame will appear stretched and distorted, creating an abstract and dynamic portrayal of urban life.

whip panning
whip panning

3. Record Propellers or Spinning Blades

The third and easiest way is to just record spinning blades or propellers because they move so fast.

As the propellers spin, the rolling shutter effect can cause them to appear fragmented or distorted. By adjusting your shutter speed and timing the capture correctly, you can enhance the effect and emphasize the sense of motion.

Experiment with different shutter speeds to achieve varying levels of distortion. A slower shutter speed can result in a more pronounced rolling shutter effect, while a faster shutter speed may produce a subtle yet visually engaging distortion.

Frequently Asked Questions

What is the advantage of rolling shutter camera?

The advantage of a rolling shutter camera is its ability to capture motion and dynamic scenes with the use of distortion.

Do mirrorless cameras have rolling shutter?

Mirrorless cameras, like other digital cameras, can experience rolling shutter artifacts due to their use of electronic shutters and CMOS sensors, although the severity can vary depending on the specific camera model and shooting conditions.

Do phone cameras use rolling shutter?

Yes, phone cameras, which often use CMOS sensors and electronic shutters, can experience rolling shutter artifacts to varying degrees depending on the specific phone model and shooting conditions.